(1) Field of the Invention
The present invention relates to the packaging of plural articles and particularly to the formation of a soft wrapper around a pre-formed grouping of articles such as, for example, a block of cigarettes. More specifically, this invention is directed to apparatus for packaging cigarettes or the like and especially to multi-stage devices for drying the glue employed to hold the folded ends of the packages formed by such apparatus in the closed state. Accordingly, the general objects of the present invention are to provide novel and improved methods and apparatus of such character.
(2) Description of the Prior Art
While not limited thereto in its utility, the present invention is particularly well suited for use in machines for packaging cigarettes. Such packaging machines form a paper wrapper around the sides of a pre-formed block of cigarettes and subsequently, in successive steps, form the opposite ends of the package by folding and gluing the wrapper. These packaging machines include a drying drum into which the packages are transferred and retained until the glue applied to the end folds has set. In the prior art these drying drums have been of single-row construction and the newly formed packages have been inserted singly into the cells of the drying drum from the apparatus which has formed the second package end. In order to prolong the drying time, it has been proposed to employ a drying drum which includes a greater number of receiving cells than does a cooperating drum of the second end forming device. This arrangement permits the packages to remain in the drying stage for two revolutions of the drum but imposes a limitation on packaging speed since it is only possible to transfer the packages from the second end forming device into the cells of the drying drum singly. Thus, attempts to increase packaging speed necessarily result in a reduction in drying time since the drying drum must move in sequence with the end forming device.
It has also been proposed to alleviate the above-discussed problem by direct heating of the cells of the drying drum. This, however, increases the complexity of the apparatus and thus increases its cost while reducing its reliability.